Monday, April 21, 2014

IP subnetting unraveled

Consider the following address in CIDR notation:

172.19.235.75 /13

1) What is the network address?

2) What is the broadcast address?

First, determine the subnet mask in dotted decimal notation: 255.248.0.0

Next, calculate: IP_Address AND Mask.  This reveals the network address as 172.16.0.0 (NET_address)

Then, determine the wildcard mask (WC_mask) by inverting 1's and 0's in the subnet mask: 0.7.255.255

Finally, calculate: NET_address OR WC_mask, and this reveals the broadcast address: 172.23.255.255

Now, practice this method on 10.0.0.100 /28 and if you are feeling adventurous, try 192.168.255.254 /22